COVID-19: Nasal vaccine shows promise in mouse study
A new study has explored an experimental COVID-19 vaccine for intranasal administration. The scientists show that just one dose may protect against infection in mice susceptible to the novel coronavirus.
The race to develop a safe and effective vaccine for SARS-CoV-2 is intensifying.
Researchers and pharmaceutical companies around the world are working around the clock to develop novel vaccines.
Although most experimental COVID-19 vaccines are injectable, a recent study in mice has investigated a vaccine for intranasal administration. People receive these types of vaccine through the nose.
The findings of the new study suggest that the vaccine acts as a shield against SARS-CoV-2 after just one dose.
The study authors recently published their research in the journal Cell. They hope to test the vaccine in nonhuman primates in the future.
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A single dose
Scientists from Washington University School of Medicine in St. Louis are developing this new intranasal vaccine.
To design it, they used an altered adenovirus. Like other viruses, adenoviruses can cause the common cold. Scientists also use them to develop a range of vaccines, including those for tuberculosis and Ebola.
Medical News Today asked senior study author Prof. Michael S. Diamond why the research team decided to look for an intranasal vaccine. He explained: “There is precedent for this with influenza vaccines. Hence, we thought we might see improved mucosal (local) immune responses in the respiratory tract that might better control SARS-CoV-2 infection.”
The team inserted the novel coronavirus’s spike protein into the adenovirus. Coronaviruses use this spike protein to colonize cells.
The researchers first modified the adenovirus to prevent it from causing illness in the mice. This benign adenovirus then works as a vehicle to carry the spike protein into the nose and prepares the body to initiate an immune defense against SARS-CoV-2.
The researchers also showed that this vaccine integrates two mutations into the spike protein. These mutations fix the spike proteins into a rigid form that promotes the formation of antibodies.
To test the efficacy of the new vaccine, the researchers gave it to mice, either intranasally or by injection. Injecting the vaccine resulted in an immune response that prevented pneumonia, but it could not prevent the infection from spreading to the lungs.
This means that an intramuscular injection of the vaccine might reduce the severity of COVID-19, but it would not stop transmission of the virus or prevent infection.
However, when the scientists administered the vaccine nasally, they observed that it prevented infection in the upper and lower respiratory tracts (the nose and lungs).
According to Prof. Diamond: “In these mouse models, the vaccine is highly protective. We’re looking forward to beginning the next round of studies and ultimately testing it in people to see if we can induce the type of protective immunity that we think not only will prevent infection but also curb pandemic transmission of this virus.”
An influenza vaccine called FluMist is also available for intranasal administration. However, because it uses a live form of the influenza virus, it is not suitable for everyone (such as people with weakened immune systems).
However, this potential new COVID-19 vaccine does not use a live virus — which, in theory, should make it safer.
As Prof. Diamond explained to MNT: “Any vaccine can cause side effects. However, because the vaccine does not replicate, it could not cause unanticipated infection the way a “live” vaccine could — in this way, it would be safer.”
“We will soon begin a study to test this intranasal vaccine in nonhuman primates with a plan to move into human clinical trials as quickly as we can.”
— Prof. Michael S. Diamond
Although they are aiming for a single nasal dose, the scientists admit that a booster dose might be necessary.
In the future, they hope to move into phases 1 and 2 of human clinical trials.
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